Tracking number of threads in threadpools.

Added tests for max total thread count.

Renamed getThreadPoolMaxThreadCount to getThreadPoolMaxTotalThreadCount
which takes into account user joined threads and polling threads.
Test added to check that the current available threads update properly
and do not lock.
Added second test that simulates a deadlock and confirms the deadlock.

Bug: 188834514
Test: binderLibTest
Change-Id: Ia99d95544a38596ec9fc316e623e523b64337bc7